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Journal ArticleDOI

Nanocomposite membranes with Au nanoparticles for dialysis-based catalytic reduction-separation of nitroaromatic compounds

01 Jan 2022-Reactive & Functional Polymers (Elsevier BV)-Vol. 170, pp 105119
TL;DR: In this paper, a new approach that enables NAR-contaminated wastewaters to be treated as a reagent for the synthesis of aromatic amines (AAMs) was presented.
Abstract: Apart from the fact that nitroaromatic compounds (NARs) have toxic and mutagenic characteristics, they are also essential substrates for the synthesis of aromatic amines (AAMs). In this context, the present study presents a new approach that enables NAR-contaminated wastewaters to be treated as a reagent for the synthesis of AAMs. It involves the fabrication of anion exchange membranes with Au nanoparticles (AuNPs) that simultaneously reduce 4-nitrophenol (4-NP) and separate the resultant 4-aminophenol (4-AP) via. the dialysis mechanism. The nanocomposite membranes were prepared by amino-modification of poly(vinyl chloride) films obtained in the presence of cyclohexanone (CH) or tetrahydrofuran (THF), followed by Au(III) reduction coupled-adsorption. The nanomaterials were analysed using scanning transmission electron microscopy (STEM) and Fourier-transformation infrared spectroscopy (FT-IR). The catalytic reaction was carried out in a dialysis unit, where the concentration of 4-NP in the wastewater, and the concentration of separated 4-AP were monitored using UV–Vis spectroscopy. The nanocomposite membranes formed using THF effectively reduced the 4-NP and separated the resultant 4-AP. The yield of the 4-NP conversion reached 80% with a rate constant of 11.30∙10–3 min−1. Based on the results, THF contributed to the formation of diffusion paths in which the 4-NP was simultaneously separated and reduced.
Citations
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Journal ArticleDOI
TL;DR: In this paper , the effective reduction of the organic pollutants, the nitroaromatics, via green sustainable chemistry using high efficacy of the catalytic materials, i.e., β-cyclodextrin (β-CD) functionalized Au nanoparticles (AuNPs), was demonstrated.

3 citations

Journal ArticleDOI
TL;DR: Graphene oxide was blended with polyvinyl alcohol film as a solid support for nickel nanoparticles as a dip catalyst as mentioned in this paper , which was employed in catalytic reduction and oxidation to get rid of Cr 6+ , 4-nitrophenol, and methylene blue as water pollutants.
Abstract: Graphene oxide was blended with poly(vinyl alcohol) film as a solid support for nickel nanoparticles as a dip catalyst. Simple preparation steps were followed avoiding the use of hazardous materials and/or any surface treatment. Graphene oxide plays the key role in the proposed catalyst by cross-linking poly(vinyl alcohol) film, increasing the affinity of the substrate for adsorbing nickel ions, and increasing the hydrophilicity of the nanocomposite. The prepared dip-catalyst was employed in catalytic reduction and oxidation to get rid of Cr 6+ , 4-nitrophenol, and methylene blue as water pollutants. A reasonable control over the operational parameters of the catalytic reaction was achieved. Significantly, the free-standing film form of the catalyst enabled the facile separation of the catalyst without release of the nickel nanoparticles. Also, the recyclability of the catalyst was investigated for several runs without any considerable loss of catalyst efficiency. The proposed catalyst fits the environmental and industrial requirements because of its stability, low cost, and activity for wide range of catalytic reactions.

2 citations

Journal ArticleDOI
TL;DR: A rod-like magnetic nanocomposite was successfully synthesized in this paper by loading Ag and Fe3O4 nanoparticles onto the surface of the hydroxyapatite/MIL-101(Fe) metal-organic framework.
Abstract: A rod-like magnetic nanocomposite was successfully synthesized in this work by loading Ag and Fe3O4 nanoparticles onto the surface of the hydroxyapatite/MIL-101(Fe) metal–organic framework. Various techniques were used to investigate the crystalline nature, size, morphology, and magnetic and structural properties of the HAP/MIL-101(Fe)/Ag/Fe3O4 nanocomposite, including X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), BET surface area measurements, and zeta potential analysis. The results indicate that the nanocomposite sample is composed of Ag and Fe3O4 nanoparticles adhered to rod-like hydroxyapatite/MIL-101(Fe). The catalytic and antibacterial abilities of the as-prepared HAP/MIL-101(Fe)/Ag/Fe3O4 were studied. This nanocomposite was utilized as a heterogeneous catalyst for the catalytic reduction of toxic pollutants, including 4-nitrophenol (4-NP), 2-nitrophenol (2-NP), 2,4-dinitrophenol (2,4-NP), 4-nitroaniline (4-NA), and 2-nitroaniline (2-NA) by NaBH4 in water and at room temperature. These compounds were converted to their amine derivatives within 8–18 min with rate constant values equal to 0.2, 0.3, 0.33, and 0.47 min−1, respectively. This quaternary magnetic catalyst can be easily separated from the reaction medium using an external magnetic field and reused. The synthesized nanocomposite maintained its efficiency in reducing nitroaromatic compounds after 5 runs, showing the high stability of the catalyst. Besides, the antibacterial activity of the nanocomposite against Gram-negative and Gram-positive bacteria was evaluated using the disk diffusion method. The inhibition zone diameter of the nanocomposite against Staphylococcus aureus, Staphylococcus saprophyticus, and Escherichia coli was measured to be 17, 14, and 12 mm, respectively.
References
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Journal ArticleDOI
21 Jul 2006-Science
TL;DR: Gold nanoparticles supported on TiO2 or Fe2O3 catalyzed the chemoselective hydrogenation of functionalized nitroarenes with H2 under mild reaction conditions that avoided the accumulation of hydroxylamines and their potential exothermic decomposition.
Abstract: The selective reduction of a nitro group when other reducible functions are present is a difficult process that often requires stoichiometric amounts of reducing agents or, if H2 is used, the addition of soluble metals. Gold nanoparticles supported on TiO2 or Fe2O3 catalyzed the chemoselective hydrogenation of functionalized nitroarenes with H2 under mild reaction conditions that avoided the accumulation of hydroxylamines and their potential exothermic decomposition. These chemoselective hydrogenation gold catalysts also provide a previously unknown route for the synthesis of the industrially relevant cyclohexanone oxime from 1-nitro-1-cyclohexene.

1,331 citations

Journal ArticleDOI
TL;DR: FeOx-supported platinum single-atom and pseudo-single-atom structures are reported as highly active, chemoselective and reusable catalysts for hydrogenation of a variety of substituted nitroarenes.
Abstract: The catalytic hydrogenation of nitroarenes is an environmentally benign technology for the production of anilines, which are key intermediates for manufacturing agrochemicals, pharmaceuticals and dyes. Most of the precious metal catalysts, however, suffer from low chemoselectivity when one or more reducible groups are present in a nitroarene molecule. Herein we report FeOx-supported platinum single-atom and pseudo-single-atom structures as highly active, chemoselective and reusable catalysts for hydrogenation of a variety of substituted nitroarenes. For hydrogenation of 3-nitrostyrene, the catalyst yields a TOF of ~1,500 h(-1), 20-fold higher than the best result reported in literature, and a selectivity to 3-aminostyrene close to 99%, the best ever achieved over platinum group metals. The superior performance can be attributed to the presence of positively charged platinum centres and the absence of Pt-Pt metallic bonding, both of which favour the preferential adsorption of nitro groups.

839 citations

Journal ArticleDOI
TL;DR: In this paper, the basic concepts and recent developments and advances of gold nanoparticle (AuNP)-catalyzed 4-nitrophenol (4-NP) reduction to 4-aminophenol by sodium borohydride, including the catalytic mechanism, the variety of stabilizers, and dendritic, natural and heterogeneous AuNP supports are presented.

632 citations